Paper feeding apparatus

ABSTRACT

A motor is driven according to a total feeding amount of a recording paper calculated based on the number of prints. When a gear is rotated in a counterclockwise direction, an end of a coil spring is moved upward and a retaining arm is rotated. A tip of a separation plate fixed to the retaining arm is moved to a contact position in which the tip contacts an outer peripheral surface of a paper roll. The separation plate presses the outer peripheral surface with a constant pressing force by a coil spring. When the paper roll is rotated, the separation plate separates a paper end. Thereafter, the gear is rotated in a clockwise direction to move the end of the coil spring downward so that the separation plate moves to a retracting position away from the outer peripheral surface. During printing, the separation plate is in the retracting position.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a paper feeding apparatus for feeding a recording paper by separating a leading end of a recording paper from an outer peripheral surface of a recording paper roll.

2. Description of the Related Art

Conventionally, a paper feeding apparatus is known which supplies a recording paper to a printing section through a paper feed port by rotating a paper roll formed by winding the continuous recording paper in a roll form. The paper feeding apparatus of this type has an end separator which contacts an outer peripheral surface of the paper roll to separate a leading end of the recording paper from the paper roll. An end separator disclosed in Japanese Patent Laid-Open Publication No. 11-011750 is biased toward the paper roll by a biasing means such as a coil spring or the like so that a tip of the end separator contacts the outer peripheral surface of the paper roll. In this state, when the paper roll is rotated, the leading end is slightly lifted by the tip of the end separator and separated from the paper roll. The separated leading end of the paper roll is guided to the paper feed port by a guide section.

However, a pressing force of the above end separator to the paper roll is reduced when a diameter of the paper roll is reduced. Accordingly, the separating performance of the end separator is reduced. Further, the end separator has a good separating performance when the diameter of the paper roll is large. However, the end separator continues to press the paper roll during the printing with the same pressing force as that in the end separation. As a result, the paper roll may have the excessive pressing force so that the recording paper may be damaged or a print failure such as print streaks may occur.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a paper feeding apparatus with a stable separating performance regardless of a roll diameter of a paper roll.

Another object of the present invention is to provide a paper feeding apparatus which prevents damages and print failures on a recording paper.

In order to achieve the above and other objects of the present invention, the paper feeding apparatus includes an end separating section able to contact an outer peripheral surface of the paper roll, a retaining section for retaining the end separating section and a biasing section for biasing the end separating section. The end separating section separates a leading end of the recording paper from the outer peripheral surface of the paper roll. The retaining section moves according to an outer diameter of the paper roll for bringing the end separating section into contact with the outer peripheral surface. The biasing section makes the end separating section contact the outer peripheral surface with an approximately constant pressing force.

The end separating section is a separation plate whose end has a wedge shape. The retaining section includes a retaining arm for retaining the separation plate and a support shaft which rotatably supports the retaining arm. The retaining arm is movable between a contact position in which the separation plate comes in contact with the outer peripheral surface at an approximately constant angle and a retracting position in which the separation plate is retracted from the paper roll. The biasing section includes a coil spring wound around the support shaft. The coil spring has a first end attached to the retaining arm and a movable second end. A rotation amount of the retaining arm and a pressing force of the separation plate are adjusted by a position of the second end. The biasing section includes a spring hook member fastened to the supporting shaft and a motor for rotating the supporting shaft. The second end of the coil spring is engaged with the spring hook member. According to the total feeding amount, the rotation of the motor is controlled and an elastic force of the coil spring is adjusted.

In an embodiment of the present invention, a stationary spring hook member is included. In the stationary spring hook member, plural engaging slots are formed for adjusting the elastic force of the coil spring. The second end of the coil spring is fit to one of the engaging slots.

In another embodiment of the present invention, a retaining section is linearly movable between a contact position in which a separation plate contacts the outer peripheral surface at an approximately constant angle and a retracting position in which the separation plate is retracted from the paper roll. A biasing section includes a coil spring. The coil spring has a first end attached to the retaining position and a linearly movable second end. The position of the retaining section and the pressing force of the separation plate are adjusted according to the position of the second end of the coil spring.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects and advantages of the present invention will become apparent from the following detailed description of the preferred embodiments of the invention when read in conjunction with the accompanying drawings, in which:

FIG. 1 is an explanatory view showing a printer including a paper feeding apparatus of the present invention;

FIG. 2 is a lateral view showing an end separating mechanism;

FIG. 3A is a front view showing a separation plate contacting a paper roll with a small roll diameter, and

FIG. 3B is a front view showing the separation plate retracted from a paper roll with a large roll diameter;

FIG. 4 is an explanatory view showing a leading end of the paper being separated from the paper roll;

FIG. 5 is a front view showing an embodiment in which a pressing force of the separation plate is adjustable; and

FIG. 6 is an explanatory view showing another embodiment of the end separating mechanism.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

As shown in FIGS. 1 and 2, in a printer 10, a paper feeding apparatus (a paper feeding section) 11, a printing section 12 which performs a printing operation according to print data, a printer controller 13 for controlling the paper feeding section 11 and the printing section 12, a print data storage 14 for storing the print data from plural terminals PC1 to PC3, and the like are disposed. The paper feeding section 11 has a paper loading chamber in which a paper roll unit 17 is removably loaded. The paper roll unit 17 is formed by winding a continuous recording paper 23 in a roll form. The printer controller 13 executes printing by inputting the print data stored in the print data storage 14 to the printing section 12 and supplying the recording paper 23 from the paper feeding section 11 to the printing section 12. At this time, the driving of the motors 18 and 19 are controlled by the printer controller 13 through a driver (not shown).

The paper roll unit 17 includes a paper roll 20 and a pair of roll holders 21. The paper roll 20 is formed by winding the continuous recording paper 23 around, for instance, a hollow cylindrical core 22 with a diameter of 60 mm. The diameter of the paper roll 20 is 150 mm when the paper roll 20 is new. The pair of roll holders 21 is attached to both ends of the core 22 such that the pair of roll holders 21 holds the paper roll 20, and rotates with the core 22. Outside the pair of roll holders 21, a pair of shafts 24 is protruded. The pair of shafts 24 is rotatably engaged with a pair of bearings 25 fixed on inner walls of the paper loading chamber. One of the shafts 24 is connected to the motor 18 through a transmission mechanism. As the roll holder 21 is rotated by the motor 18, the paper roll 20 is rotated in a clockwise direction.

Around an outer periphery of the paper roll unit 17 and on both sides of a paper feeding passage to the printing section 12, guide plates 26 are disposed for guiding the recording paper 23 separated from the paper roll 20. In a part of the paper feeding passage, a separation plate 28 of an end separating mechanism 27 is disposed.

The end separating mechanism 27 is constituted of the separation plate 28, a retaining arm 29, a supporting shaft 30, a gear 31, a spring hook member 32, a coil spring 33 and the like. Before feeding the recording paper 23, the end separating mechanism 27 separates a leading end of the recording paper 23 from the outer peripheral surface of the paper roll 20 by bringing the separation plate 28 into contact with the outer peripheral surface. The spring hook member 32 is fixed to the supporting shaft 30.

The separation plate 28 and the retaining arm 29 are connected through a fixing rod 35 to bend in L-shape. For this configuration, even when the roll diameter of the paper roll 20 is changed, a tip 28 a of the separation plate 28 is able to contact the outer peripheral surface of the paper roll 20 at an approximately constant angle. A width of the separation plate 28 corresponds to the width of the recording paper 23. The tip 28 a of the separation plate 28 is formed in a wedge shape. The thickness of the tip 28 a is thinner than the thickness of the recording paper 23. Note that the width of the separation plate 28 can be shorter than that of the recording paper 23. Further, the separation plate 28 with an approximately half the width of the recording paper 23 can be disposed to one side of the paper roll 20 to come in contact with the paper roll 20.

In the retaining arm 29, a shaft hole 29 a is provided at an opposite end (an attaching end) to the fixing rod 35. Through the shaft hole 29 a, the supporting shaft 30 is rotatably inserted. A gear 31 is fixed to the supporting shaft 30. In a center portion of the retaining arm 29, an engaging slot 29 b is provided. An end 33 b of the coil spring 33 is engaged to the engaging slot 29 b.

The gear 31 is rotated by the motor 19. Along with the rotation of the gear 31, the spring hook member 32 is rotated together with the supporting shaft 30. The spring hook member 32 is fixed to the supporting shaft 30 by a screw 34. A groove 32 a is formed in the spring hook member 32. Another end 33 a of the coil spring 33 is hooked to the groove 32 a.

As mentioned above, the end 33 b of the coil spring 33 is engaged to the rotatable retaining arm 29. The other end 33 a of the coil spring 33 is hooked to the spring hook member 32. The coil section 33 c of the coil spring 33 is wound around the supporting shaft 30. As a result, the separation plate 28 is biased with a predetermined pressing force toward the paper roll 20 through the retaining arm 29 by an elastic force of the coil spring 33.

The recording paper roll 20 changes in diameter as it is used. In the present invention, the position of the end 33 a of the coil spring 33 is adjusted by rotating the spring hook member 32 with the gear 31. Thereby, the separation plate 28 is moved between a contact position (see FIGS. 1 and 3A) in which the tip 28 a contacts the outer peripheral surface of the paper roll 20 and a retracting position (see FIG. 3B). Even when the diameter of the paper roll 20 is changed, the tip 28 a of the separation plate 28 will contact the outer peripheral surface of the paper roll 20 with a predetermined pressing force.

A function of the end separating mechanism 27 is described in details. As shown in FIG. 3A, when the gear 31 is rotated by, for instance, ⊖1 in the counterclockwise direction, the spring hook member 32 is rotated around the supporting shaft 30 by ⊖1 in the counterclockwise direction in accordance with the above rotation. At this time, the end 33 a of the coil spring 33 is moved upward so that the separation plate 28 and the retaining arm 29 are moved by the elastic force of the coil spring 33 toward the paper roll 20 and the tip 28 a comes in contact with the outer peripheral surface of the paper roll 20 (the contact position). In the contact position, the separation plate 28 presses the outer peripheral surface with the constant pressing force. As shown in FIG. 3B, when the gear 31 is rotated by ⊖2 (⊖1>⊖2) in the clockwise direction, the end 33 a moves downward. Accordingly, the elastic force of the coil spring 33 is reduced such that the separation plate 28 is moved to the retracting position in which the separation plate 28 is retracted from the paper roll 20. The tip 28 a is moved away from the outer peripheral surface by a vertical distance L1.

Thus, the pressing force of the coil spring 33 is changed by adjusting the position of the end 33 a of the coil spring 33 so that the tip 28 a of the separation plate 28 presses the outer peripheral surface of the paper roll 20 with the constant pressing force. As a result, the separation performance becomes stable regardless of the diameter of the paper roll 20.

A position adjustment method of the end 33 a of the coil spring 33 is explained. In the printer controller 13, a counter 15 for counting the number of prints is provided. The counter 15 counts the number of prints, that is, the number of times that the print instruction signals are input to the printing section 12 after the paper roll 20 is replaced. Since the print size is constant, the printer controller 13 calculates a total feeding amount (the amount to be used) of the recording paper 23 according to the counted value, and generates the drive pulse of the motor 19 according to the total feeding amount. Then, the printer controller 13 inputs the drive pulse to a driver (not shown) and controls the motor 19 with very high precision. By this control, the spring hook member 32 is rotated by a predetermined angle in a predetermined direction to adjust the position of the end 33 a of the coil spring 33.

Referring to FIG. 4, a process of separating the leading end of the recording paper 23 from the paper roll 20 is described. When the paper roll 20 is rotated in a state that the paper end is adhered to the outer peripheral surface of the paper roll 20, the tip 28 a of the separation plate 28 firstly comes in contact with the paper end. Then, as the paper roll 20 is further rotated, the outermost surface of the paper roll 20 is unwound and the leading end of the paper is lifted onto the upper surface of the separation plate 28 (a state shown in a broken line). Thus, the leading end of the recording paper is separated from the outer peripheral surface of the paper roll 20 and supplied to the printing section 12.

Next, the operation of the above configuration is described. Before printing, the print data is input from any of the PCs 1-3 to the print data storage 14 and stored.

When the printing operation is instructed, the printer controller 13 calculates the total feeding amount of the recording paper 23 according to the number of prints shown as the counted value in the counter, and drives the motor 19 according to the total feeding amount. The gear 31 is rotated by the motor at an angle corresponding to the counted value in the counterclockwise direction. Thereby, the end 33 a of the coil spring 33 is moved upward and the tip 28 a of the separation plate 28 is moved to the contact position in which the tip 28 a contacts the outer peripheral surface of the paper roll 20. At this time, the outer peripheral surface of the paper roll 20 is pressed by the tip 28 a with a constant pressing force. Thereafter, when the paper roll 20 is rotated in the clockwise direction by the motor 18, the paper end is lifted and separated from the outer peripheral surface. The separated paper end moves along the separation plate 28 and is supplied to the printing section 12 through a paper feed port 11 a.

After the paper end is separated, the separation plate 28 is moved from the contact position to the retracting position. In particular, when the motor 19 is driven by the printer controller 13 to rotate the gear 31 in the clockwise direction, the end 33 a of the coil spring 33 is moved downward and the separation plate 28 is moved to the retracting position. Thus, the paper roll 20 is rotated in a state that the tip 28 a of the separation plate 28 is retracted from the outer peripheral surface. In this state, the recording paper 23 is sequentially fed to the printer 10 and the printing operation is started.

In the above embodiment, the coil spring 33 is used as a biasing means. However, the biasing means is not limited to the coil spring. A plate spring or other elastic materials with the spring-like property can be used.

In the above embodiment, the total feeding amount is calculated from the counted value of the number of the prints. The diameter of the paper roll 20 is then calculated according to the total feeding amount. The motor 19 is controlled according to the calculated roll diameter. Note that instead of the calculation, the roll diameter can be measured by using a distance measuring device with an optical sensor.

In the above embodiment, the end 33 a of the coil spring 33 is moved by the motor 19 through the gear 31. However, the end 33 a can be moved manually. For instance, as shown in FIG. 5, a spring hook member 45 of a fan-like shape is fastened to a supporting shaft 44 which is fixed not to be rotated. In the spring hook member 45, plural engaging slots 45 a are formed at constant intervals in circumferential direction. According to the amount of the paper roll used, a position of an end 46 a of a coil spring 46 is changed stepwise by sequentially shifting the position of the end 46 a within the plural engaging slots 45 a.

In an embodiment shown in FIG. 6, an end separating mechanism 51 is constituted of a separation plate 52, a retaining block 55 for retaining the separation plate 52, a coil spring 53 for biasing the separation plate 52 with an approximately constant pressing force toward the paper roll 20 through the retaining block 55 and a shift mechanism 54 which moves in an up-and-down direction. The separation plate 52 is linearly moved by the shift mechanism 54 in the up-and-down direction through the coil spring 53. Thereby, the separation plate 52 moves between a contact position in which a tip 52 a contacts the outer peripheral surface of the paper roll 20 and a retracting position in which the tip 52 a is retracted from the outer peripheral surface.

Although the present invention has been fully described by way of the preferred embodiments thereof with reference to the accompanying drawings, various changes and modifications will be apparent to those having skill in this field. Therefore, unless otherwise these changes and modifications depart from the scope of the present invention, they should be construed as included therein. 

1. A paper feeding apparatus for a paper roll formed by winding a continuous recording paper in a roll form, said paper feeding apparatus feeding said recording paper by rotating said paper roll, said paper feeding apparatus comprising: an end separating section able to contact an outer peripheral surface of said paper roll, said end separating section separating a leading end of said recording paper from said outer peripheral surface; a retaining section for retaining said end separating section, said retaining section moving according to an outer diameter of said paper roll for bringing said end separating section into contact with said outer peripheral surface; and a biasing section for biasing said end separating section such that said end separating section contacting said outer peripheral surface with an approximately constant pressing force.
 2. A paper feeding apparatus according to claim 1, wherein said end separating section is a separation plate whose end has a wedge shape.
 3. A paper feeding apparatus according to claim 2, said retaining section including: a retaining arm for retaining said separation plate, said retaining arm being movable between a contact position in which said separation plate comes in contact with said outer peripheral surface at an approximately constant angle and a retracting position in which said separation plate being retracted from said paper roll; and a support shaft for rotatably supporting said retaining arm.
 4. A paper feeding apparatus according to claim 3, wherein said biasing section includes a coil spring wound around said support shaft, said coil spring has a first end attached to said retaining arm and a movable second end, a rotation amount of said retaining arm and a pressing force of said separation plate are adjusted according to a position of said second end.
 5. A paper feeding apparatus according to claim 4, said biasing section further including: a spring hook member fixed to said supporting shaft, said second end of said coil spring being engaged with said spring hook member; and a motor for rotating said supporting shaft.
 6. A paper feeding apparatus according to claim 5, further including: an integrator for integrating a total feeding amount of said recording paper; and a controller for controlling a rotation amount of said motor according to said total feeding amount.
 7. A paper feeding apparatus according to claim 4, further including: a stationary spring hook member, said stationary spring hook member having plural engaging slots for adjusting an elastic force of said coil spring, said second end of said coil spring fitting to one of said engaging slots.
 8. A paper feeding apparatus according to claim 2, wherein said retaining section is linearly movable between a contact position in which said separation plate contacts said outer peripheral surface at an approximately constant angle and a retracting position in which said separation plate is retracted from said paper roll.
 9. A paper feeding apparatus according to claim 8, wherein said biasing section includes a coil spring, said coil spring has a first end attached to said retaining section and a linearly movable second end, a position of said retaining section and a pressing force of said separation plate are adjusted according to a position of said second end. 